FK506, Denudation of Donor Endothelial Cells and Bafilomycin A_1, a Selective Inhibitor of Vacuolar H^+-ATPase, Inhibit Neointimal Hyperplasia in Rat Cryopreserved Aortic Allograft

冷冻保存的同种异体移植物已被用作自体移植物的替代品。然而，同种异体移植物的质量受到新生内膜增生（NH）的影响。尽管同种异体免疫反应和冷冻保存程序与冷冻保存同种异体移植物病变的机制有关，但这种病理生理学的确切性质仍不清楚。因此，我们研究了在大鼠低温保存的同种异体主动脉移植中异体免疫反应和v - atp酶在NH中的可能参与。将冷冻保存的供体大鼠胸主动脉植入受体大鼠肾下腹主动脉。术后14天切除的移植物通过计数CD8^+免疫染色阳性淋巴细胞的数量（×10^4/mm^2）和计算内膜/中膜面积比的NH来评估全免疫反应。同种异体移植物未处理和BA_1处理的同种异体移植物的同种免疫应答显著高于未处理的同种异体移植物、FK506处理的同种异体移植物和剥去内皮细胞的同种异体移植物（p<0.05）。未处理的同种异体移植物和移植前剥去ETs的同种异体移植物，与未处理的同种异体移植物相比，FK506和BA_1对NH的抑制作用显著（p<0.05）。新生内膜细胞vimentin免疫染色阳性，但HF-35和CGA-7免疫染色阴性，提示这些细胞为去分化的SMCs。FK506、供体ETs的剥落和BA_1对大鼠同种异体主动脉移植后早期NH有抑制作用。抑制异体免疫应答诱导的NH抑制机制可能与免疫抑制有关，而BA_1的抑制机制可能是通过抑制V-ATPase直接抑制去分化SMCs的生长。

Cryopreserved allografts have been utilized as alternatives for autografts. However, quality of allografts has been compromised by neointimal hyperplasia (NH). Although allo-immune response and cryopreservation procedures have been implicated in the mechanism of cryopreserved allograftpathy, the exact nature of this pathophysiology remains unknown. We have, therefore, investigated the possible involvement of allo-immune response and V-ATPase in NH in rat cryopreserved aortic allografts.Cryopreserved thoracic aorta from donor rats were implanted to the infra-renal abdominal aorta of recipient rats. The grafts removed 14 days after surgery were evaluated for all-immune response by counting the number of lymphocytes with positive immunostainung for CD8^+(×10^4/mm^2), and for NH by calculating the area ratio of intima to media.Allo-immune response in untreated allografts and allografts treated with Bafilomycin A_1 (BA_1) were significantly higher than untreated isografts, allografts treated with FK506 and allografts of which endothelial cell (ETs) were denuded (p<0.05). Untreated isografts and allografts of which ETs were denuded before transplantation and treated with FK506 and with BA_1 showed significant inhibition of NH compared to untreated allografts (p<0.05). Neointimal cells showed positive immunostaining for vimentin, but negative for HF-35 and CGA-7, indicating that these cells were dedifferentiated SMCs.FK506, denudation of donor ETs and BA_1 inhibit NH early after transplantation of rat cryopreserved aortic allografts. The mechanism of inhibition of NH induced by inhibition of allo-immune response may involve immunosuppression whereas that exerted by BA_1 may be mediated through direct growth suppression of dedifferentiated SMCs via inhibition of V-ATPase.